[Amps] construct ferrite "line isolator"

[Jim Brown]

On 10/25/2010 9:52 AM, tzikas tzik wrote:
> I have problem with R.F interference from linear amplifier or antenna to pll
> unit. I believe that i have ground loops. I have read some relative
> articles:
> http://www.radioworks.com/nbgnd.html
> http://www.airmail2000.com/rfi.htm
> This articles propose to use ferrite "line isolator" between pll and linear
> amplifier (in the coaxial cable RG58) and in the output coaxial cable
> (RG214).
> i have many ferrite beads (material 43) FB-43-7351 and FB-43-1020. How i can
> construct these "line isolatosr".Do you have any schematic? thank you very
> much.

Both of these references are way off base.

I strongly suggest that you study my RFI tutorial, paying careful 
attention to the discussion of "the pin 1 problem" and the discussion of 
ferrite chokes.  In general, ferrite beads are useless at HF frequencies.

http://audiosystemsgroup.com/RFI-Ham.pdf

73, Jim Brown K9YC